Insecticidal compositions and method of using same



States Patent INSECTICIDAL COMPOSITIONS AND METHOD OF USING SAME Fred Smith, Wayzata, and Laurence K. Cutkomp, St.

Paul, Minn., and Abdel Aziz Fathy, Giza, Egypt, assignors to Regents of the University of Minnesota, Minneapolis, Minn, a corporation of Minnesota No Drawing. Application October 2, 1952 Serial No. 312,854

13 Claims. (Cl. 167-22) salts, perfluoro esters and salts, and copper chelates of keto esters. These various compounds may be represented by the following formulae:

The perfluoro ketones may be represented by the formula O in which R and R are, respectively, an alkyl group and a perfluoro alkyl group containing from 1 to carbon atoms. In addition to these monomers the base catalyzed polymers of such ketones have been found to be particularly efiective. With reference to the monomeric ketones themselves it has been found that those which contain at least 4 carbon atoms in the perfluoro alkyl radical are preferred.

The perfluoro diketones may be represented by the formula RCR-CR l t in which R and R are alkyl groups containing from 1 to in which R is a lower alkyl group or an alkali metal, such as sodium or potassium, and in which R is a perfluoro alkyl group containing from 1 to 20 carbon atoms.

Another group of compounds are the esters and salts of perfluoro dibasic acid having the formula ROOCR"COOR in which R is a lower alkyl group or an alkali metal and alkyl group containing from l to 20 R" is a perfluoro carbon atoms.

A.further group of compounds suitable for the present invention are the copper chelates represented by theformula) v V j Cu(Rf|JoHOooR O ice in which R is a perfluoro alkyl group containing from 1 to 20 carbon atoms and R is a lower alkyl group.

It is therefore an object of the present invention to provide novel pesticidal compositions and particularly novel insecticidal compositions containing the above compounds and to provide a novel'process of destroying such pests involving the application of these compounds to the material to be treated.

The preparation of typical materials within the class of compounds described above is describedhereinafter. Of the monomeric ketones those in which the perfluoro alkyl group and the alkyl group contain from 1 to 4carbon atoms are more readily available because of the more ready availability of the starting materials. However, the monomeric ketones containing in excess of 4 carbon atoms in the perfluoro alkyl group are preferred because of their increased effectiveness as from 1 to 4 carbon atoms, it is preferred to prepare the polymeric perfluoro alkyl ketones from these lower alkyl ketones since these polymers are extremely effective for the purposes described. In this base catalyzed polymerization any of the usual strong basic catalysts may be used. Typical basic catalysts include the alkali metals,

sodium and potassium; the alkali metal hydroxides, such as sodium and potassium hydroxide; barium hydroxide, sodium amide, potassium amide, lithium amide, sodiumand potassium hydrides, and the like. The nature of the polymer which is formed is not definitely established and accordingly applicants do not desire to be bound by any particular theory. polymer obtained from trifluoro acetone (CF .CO.CH for example, is a cyclic trimer.

While it has been found that the monomeric ketonescontaining 4 or more carbon atoms in the perfluoro alkyl group and the polymers of all of the monomeric perfluoro alkyl ketones are far superior in their effectiveness to the other compounds herein described, the remaining compounds are effective for the purposes of the invention and may be used. more effective compounds are preferred.

The following list of compounds have been tested bythe methods herein described and have been found to' be effective insecticides:

In use these materials may be employed in a variety of 7 Ways. They may be used in the form of a dust for which purpose any conventional inert solid carrier may be used.

They may be used as aqueous dispersions or emulsions or may be used in a solution in a suitable solvent. may be used in the liquid phase. or in the vapor phase as a fumigant or may be suitably combined with a solvent Patented May 13,1958

pesticides and as insecticides. The base catalyzed polymers of all of these monomers are extremely effective as insecticides even Where the alkyl group and the perfluoro alkyl group contain only a single carbon atom. In view of the ready availability therefore of the monomeric ketones containing It is postulated, however, that the It is apparent, however, that the much They I so the material may be used in the form of an aerosol. In the preparation of aqueous dispersions or emulsions some of the lower members of the series may be directly soluble in water. Those which are not so soluble may be dissolved in a suitable solvent, such as a ketone solvent, preferably the lower alkyl ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone and the like. The solution of the material and the solvent may be then dispersed in a very weak aqueous dispersion or emulsion. Dispersions containing 1 part per million of these compounds demonstrate a phenomenal kill of mosquitoes and mosquito larvae as well as other pests.

Preparation of active materials Ethyl trifluoro-acetate was prepared from trifluoro acetic acid by esterificaiton with ethanol in the presence of a sulfuric acid catalyst. The ester was worked up by washing, drying and distillation.

Ethyl tn'fluoro acetoacetate was prepared from ethyl trifluoro acetate as follows: Dry ethyl trifluoro acetate was added dropwise to a flask containing anhydrous ether and dried sodium ethoxide. The solution was boiled under reflux for about 21 hours and then allowed to stand at room temperature for an additional 48 hours. A portion of this product was worked up for ethyl trifluoro acetoacetate by placing it in a separatory funnel, which was then left in a cold room for a few hours. Cold dilute sulfuric acid was then added and the ethereal layer was separated and the aqueous layer extracted with ether repeatedly. The ether extract was then washed and dried. The product was distilled and the fiuoro ester distilled at 131.5 C.

The copper chelate of ethyl trifluoro acetoacetate was prepared by reacting a solution of the ester in ethanol with a saturated aqueous solution of cupric acetate. The reaction was carried out on a steam bath for a few minutes with shaking, after which the product was placed in the cold to yield crystals which were filtered off and washed with water. Recrystallization from ethanol gave the chelate in the form of bluish-green crystals melting at 188-189 C.

Trifluoro acetone was obtained from the remainder of the ethereal solution containing the condensation product obtained during the synthesis of ethyl trifluoro acetoacetate. The ether was distilled from the solution and the residue was placed in a flask containing ice, to which 9 N sulfuric acid was added. The fractionating column was attached to the flask, the column was connected to a condenser which led to a receiver cooled in a solid carbon dioxide-acetone mixture. A drying tube was attached to the receiver. The delivery tube from the condenser reached almost to the bottom of the receiver which contained ether. The temperature of the oil bath was raised slowly to 80 C. and kept at that temperature for four hours, after which all the 'free oily ethyl trifluoro-acetoacetate had decomposed to ethyl alcohol andcarbon dioxide and trifluoro acetone which passed on to the receiver. Phosphorous pentoxide was added to the receiver and the trifluoro acetone was re-distilled by raising the temperature to 40 C. and receiving the gas in a similar receiver containing anhydrous ether and immersed in a solid carbon dioxide-acetone mixture.

The trimer of trifluoro-acetone was prepared by employing sodium metal. with a small amount of mercury. About six moles of birdshot sodium were used per mole of trifluoro-acetone. The sodium particles were washed several times with anhydrous ether (dried over sodium), thenadded to a three-neck round-bottom flask equipped with an electric stirrer fitted with a mercury seal, a condenser. leading to a trap immersed in a solid carbon dioxideacetone mixture, and a separatory funnel. Extreme precautions were taken to exclude .the ingress of any moisture, either to the trap or to the reaction flask. Through the funnel anhydrous ether (100 ml.) was added to. cover the sodium granules. The ethereal solution containing trifluoro acetone, which had been stored at a temperature of minus C., was poured into the separatory funnel and added gently with stirring to the sodium and ether. A reaction was noticed at the beginning by formation of bubbles around the sodium granules and later by the solution of the reaction mixture becoming darker as the reaction proceeded. When all the ethereal solution of the ketone had been added, stirring under reflux was continued at room temperature for 6 hours. Then all of the trifluoro-acetone and other that escaped to the trap was returned to the reaction mixture. Clean mercury (2 g.) was added and the mixture refluxed gently for 36 hours, stirring being continuous. Every six hours the reaction flask was cooled to room temperature and the solution that had escaped to the trap was returned to the reaction flask. Finally the reaction was left for 12 more hours at room temperature.

The ethereal solution was decanted and acidified with dilute sulfuric acid. The aqueous layer was extracted four times with ether and finally the other extracts were washed twice with small portions of cold water to eliminate any acid. The ethereal extract was then dried over anhydrous sodium sulfate for 12 hours and subjected to distillation. The main product distilled at about 90 C. under water pump vacuum (about 17 mm.) as a viscous liquid. This liquid was dissolved in hot dry petroleum ether (boiling range to C.) and upon concentration and cooling white needle-like crystals were obtained. Recrystallization by the same method was followed and crystals of the same properties were obtained. The crystals melted at 96 C. The product was analyzed for carbon and hydrogen with the following results:

Theory for the trimer of trifluoro acetone-C, 32.15; found, 32.8. H, 2.70; found, 3.06.

The other compounds listed underthe toxicity tests were prepared from the corresponding perfluoro acid by a series of reactions similar to those described previously with reference to trifluoro acetic acid.

40 T oxzczty tests Sodium trifluoro acetate and sodium perfluoro caproatewere dissolved in water to yield solutions containing 30 mg. of the salt in 5 ml. of water. 2 cubic mm. of this solution were injected into each of a number of milkweed bugs (Oncopeltus fasciatus); this dose equalled 200 micrograms of the compound per gram of body weight. The milkweed bugs were first chilled in a refrigerator at 28 to 30 F. for 30 minutes, which permitted the injection of the compounds without causing any noticeable injury to the bugs. Injection was made successfully through the membrane between the last thoracic and first abdominal segments on the ventral side of the insect. The injected insects (10 per compound) were placed in Petri dishes and left at 30 F. for a period of 3 days. A small piece of cotton moistened with water and a few milkweed seeds were placed in each Petri dish to provide-the insects with food and water. The results obtained are indicated in the following table:

Ethyl trifluoro acetate, ethyl perfluoro caproate, and diethyl tetrafluoro succinate were used on milkweed bugs in the following manner: Solutionsofthese esters were made in acetone with concentrations'that provided 100 milkweed bugs were then treated exactly'a's described h the previous experiment using 2 cu. mm. of the solution and 4 cu. mm. of the solution. The results obtained Ten replications per compound; 10- 2 insects l replication.

A series of perfluoro ketones was tested on adult mosquitoes (Aedes aegypti) in a manner similar to that are indicated in the following table: previously described The results are indicated in the Time after application in hours Dose, Volume, Compound mgJkg. 'cu. mm. 12 24 36 48 A D A D A D A D A nntnno 2 9 0 9 g I i g 1 200 2 2 9 v 5 oFl-ooim 1 I 4 3 g 18 g i g g 2 iFll- OIE t 40 4 11 O 8 3 '6 4 6 5 200 2 11 1 10 2 1 2 s 4 (Om-001m) 400 4 10 2 10 2 9 3 7 5 Anptrme 4 9 o 9 0 7 2 7 2 A=number alive; D=number dead.

Ethyl trifiuoro acetate, ethyl perfluoro caproate, diethyl following table: tetrafluoro succinate and diethyl octafluoro adipate were used on the flesh fly (Sarcophaga bullata, Park). 8 mg. Dose, Percent Timer Compound mg. per No.0f knockdown complete of each of the esters were dissolved m 10 ml. of acetone Sq. ft Adults after 2 knockdown so that each cubic millimeter contained 0.8 mrcrogram. hours A volume of 6 cu. mm. was applied topically per insect. This dose equals 40 mg./kg. of body weight. The insects Acetone 92 2 4 IRS. were placed in Petri dishes and kept under observation 23g 32 g 3% u rs. for 48 hours at C. Flve insects were employed for s2 0 Zlfirs. e4 40 2 rs. each compound. The results are indicated in the fol 200 70 100 1H0 mm lowing table: 200 120 100 2-5 min 200 154 100 2-5 min. 35 (OH oo'or) l i T. aft ll a. 2 2 m Compound empp canon (OHLOCLOFLOFQQUUW 50 l 97 100 5-10 min.

sass-8a 22 s s 1 hr. 24 36h 48h a- 2 1 5 r.

2 hr r r OHs.OO.CF2.0F2)2-- 25 48 100 60-90 min. DDT--. 20 181 100 so min. Dead. Dead Dead Dead o 0 o c 40 f i The trifluoro acetone trimer was tested on mosquito (Et.O:O.CFz)z:- 0 l o 1 3 larvae as follows: The trimer was dissolved in acetone 1 2 2 2 and mixed with water by taking a certain volume of the Ethyl pentafluoro propiono acetate and its cupric chelate, hepta fiuoro butyro acetate and its cupric chelate and the cupric chelate of ethyl trifiuoro aceto acetate were tested on the adult mosquitoes (Aedes negypti). The compounds were dissolved in acetone in a concentration of 28 mg. per ml. A volume of 0.5 milliliter of these solutions was distributed to wet evenly the filter paper covering the bottom of Petri dishes having an area of 0.07 square foot. This dose is similar to about 200 mg. per square foot. In other instances the filter paper was covered at the rate of mg. per square foot. The dishes were then left uncovered for about two minutes until the acetone volatilized. Insects were placed in the Petri dishes and counts were taken for knockdowns at intervals of 30 minutes. The total time of exposure was 4 hours. Insects that were knocked down did not recover. The results obtained are indicated in the following table:

acetone solution in a pipette and releasing the solution under the surface of the water with gentle stirring. The;

final concentrations of these compounds were 0.1, 0.01 and 0.001 per cent (weight/volume) and each concentration had 1 percent (volume/volume) acetone. The

' larvae were kept in contact with these solutions for 72 hours at 30 C. and counts were taken for insectsv killed during the first 18 hours and at the end of 72 hours. i

Forty larvae were used for each compound in lots of 1 ten each. The results are indicated in the following table:

Percent Mortality Percent after- Oompound Ooncen- 1 tratlon 18 hr. 72 hr.

Acetone r 1 12. 5 12. 5 Trlfluoroacetone. trlmer 0. 1 100 v100 The trifluoroacetone trimer and pentafluoro ethyl meth: yl ketone were dissolved in acetone and were tried on adult j mosquitoes, (A edes aegypti) A volume of one ml."

(containing 1.4 mg. o'f'the' ketone) was delivered evenly on the bottom of the Petri dish (area, 0.07 sq. ft.) without using filter paper. After all of the acetone had evapoi' ,7 was also tried at 30 mg./sq. ft. The results obtained are indicated in the following table:

Compound Dose, No. of Time for 100% mg/sq. it. Insects Knockdown Acetone (1 1111.2) 23g :ilgot affected.

mm. Tnfiuoroacctone trimer 30 320 1:3 mm Pentafluoro ethyl methyl ketone 120 -60 min.

polymer. DDT 20 180 30 min.

formula:

RCR i l in which R and R are, respectively, an alkyl group and a perfluoro alkyl group, each containing from 1 to 20 carbon atoms, and n is a whole number from 1 to 3, and acarrier therefor.

2. The method of killing pests which comprises distributing an insecticidal composition of matter including a compound having the formula:

in which R and R are alkyl groups containing from 1 to 20 carbon atoms and R" is a divalent perfluoro alkyl group containing from 1 to 20 carbon atoms, and a carrier therefor to effect contact of said chemical compound with the-pests.

3. The method of killing pests which comprises distributing an insecticidal composition of matter including a compound having the following formula:

in which R is a lower alkyl group and R is a perfluoro alkyhgroupcontaining from 1 to 20 carbon atoms, and a carrier therefor tocifect contact of'said chemical compound witli thepests.

4. An insecticidalcomposition of. matter comprising a polymer of a compound having the following formula:

in which Rand R. are, respectively, an alkyl group and a per-fluoro alkyl group, each containing from 1 to 20 carbon atoms,;and a carrier therefor.

5. An insecticidal composition of matter comprising a polymer of a. compound having. thev following formula:

[R-C-R] ll in which R and R are, respectivelygan alkyl group and a perfluoroalkyllgroup, eachcontaining from 1 to 20 carbon atoms,- and a finely divided. inert powder carrier.

6. An insecticidal composition of matter comprising a polymer of a compound having the following formula:

in which R and R are, respectively, an alkyl group and a perfluoro alkyl group, each containing from 1 to 20 carbon atoms, in an aqueous emulsion.

7. An insecticidal composition of matter comprising a polymer of a compound having the following formula:

formula:

in which R is the lower alkyl group containing from 1 to 4 carbon atoms and R' is a perfluoro alkyl group containing from 4 to 20 carbon atoms, and n is a whole numher from i to 3, and a carrier therefor.

9. The method of killing pests which comprises distributing the combination of a chemical compound selected from the group consisting of pei'fluoroalkyl ketones, dimers and trimers thereof, perfluoro alkyl diketones, perfluoro alkyl keto esters, perfluoro alkyl esters and alkali metal salts of perfluoroalkyl-monoand dibasic acids and copper chclates of perfluoro alkyl keto acids wherein the per-fluoro alkyl radical of each member of said group contains from 1 to 20 carbon atoms, and a carrier therefor to effect contact of said chemical compound with said pests.

10. The method of killing pests which comprises distributing the combination of a trimer of trifluoro acetone and a carrier therefor to efiect contact of said chemical compound wth the pests.

11. The process of killing pests which comprises distributing "the combination of a chemical compound having the following formula:

in which R is a lower alkyl group containing from 1 to 4 carbon atoms and R is a perfluoro alkyl group containing from 1 to 20 carbon atoms, and n is a whole number from l to 3, and a carrier therefor to eifect contact of said chemical compound with the pests.

12. The method of killing pests which comprises distributing the combination of perfluoroheptyl methyl ketone and a carrier therefor to efiect contact of said chemical compound with the pests.

13. An insecticidal composition of matter comprising a trimer of trifiuoro acetone and a carrier therefor.

References Cited in the file of this patent UNITED STATES PATENTS 2,061,186 Cole Nov. 17, 1936 2,453,146 McBee Nov. 9, 1948 2,469,340 Payne May 3, 1949 2,559,629 Berry July 10, 1951 FOREIGN PATENTS 483,711 Canada June 3, 1952 

4. AN INSECTICIDAL COMPOSITION OF MATTER COMPRISING A POLYMER OF A COMPOUND HAVING THE FOLLOWING FORMULA: 